Concept:
To evaluate $f^{-1}(g(x))$, we must first determine the inverse of the function $f(x)$, denoted as $f^{-1}(x)$, and then substitute $g(x)$ into it.
Step 1: Find the inverse function of f(x).
Let $y = f(x)$.
$$y = x + 1$$
Swap $x$ and $y$ to solve for the inverse:
$$x = y + 1$$
$$y = x - 1$$
Therefore, the inverse function is:
$$f^{-1}(x) = x - 1$$
Step 2: Substitute g(x) into the inverse function.
We are tasked with finding $f^{-1}(g(x))$. We take our result from Step 1 and replace $x$ with $g(x)$:
$$f^{-1}(g(x)) = g(x) - 1$$
Step 3: Insert the expression for g(x).
Given $g(x) = x^3$, substitute this into the equation from Step 2:
$$f^{-1}(g(x)) = x^3 - 1$$